Characterization of Seafood Proteins Causing Allergic Diseases

[Extract] Food allergy is increasing at a faster rate than any other allergic disorder (Gupta et al., 2007). In the last few decades, a large movement toward healthier eating makes seafood one of the major foods consumed worldwide (Wild & Lehrer, 2005). Consequently, the international trade of seafood has been growing rapidly, which reflects the popularity and frequency of consumption worldwide. The United States has become the third largest consumer of seafood in the world, with 1.86 billion kg of crustaceans in 2007 (6.04 kg/capita/year)(Food and Agriculture Organisation, 2007). Since seafood ingestion can cause severe acute hypersensitivity reactions and is recognized as one of the most common food allergies, the increased production and consumption of seafood has resulted in more frequent health problems (Lopata & Lehrer, 2009; Lopata et al., 2010). Exposure to seafood can cause a variety of health problems, including gastrointestinal disorders, urticaria, immunoglobulin E (IgE)-mediated asthma and anaphylaxis (Bang et al., 2005; Lopata & Lehrer, 2009; Malo & Cartier, 1993; Sicherer et al., 2004; Wild & Lehrer, 2005)

Relationship between serum omega-3 fatty acid and asthma endpoints

Recent studies have highlighted the potential protective role of omega-3 polyunsaturated fatty acids (n-3 PUFA) in asthma. This study aimed at determining the association between seafood intake, serum PUFA composition and clinical endpoints of asthma in adults. A cross-sectional study of 642 subjects used the European Committee Respiratory Health Survey (ECRHS) questionnaire, skin prick tests, spirometry and methacholine challenge tests following ATS guidelines. Sera was analysed for n-3 and n-6 PUFA composition. Subjects had a mean age of 34 years, were largely female (65%) and 51% were current smokers. While 99% reported fish consumption, rock lobster, mussels, squid and abalone were also consumed less frequently. The prevalence of asthma symptoms was 11%, current asthma (ECRHS definition) was 8% and non-specific bronchial hyperresponsiveness (NSBH) was much higher (26%) In adjusted models the n-3 PUFAs 20:5 (EPA) and 22:5 (DPA) were significantly associated with a decreased risk of having NSBH. Total n-3 PUFA composition was associated with decreased NSBH risk (OR = 0.92), while high n-6 PUFA composition was associated with an increased risk (OR = 1.14)

Cross-reactive epitopes and their role in food allergy

Allergenic cross-reactivity among food allergens complicates the diagnosis and management of food allergy. This can result in many patients being sensitized (having allergen-specific IgE) to foods without exhibiting clinical reactivity. Some food groups such as shellfish, fish, tree nuts, and peanuts have very high rates of cross-reactivity. In contrast, relatively low rates are noted for grains and milk, whereas many other food families have variable rates of cross-reactivity or are not well studied. Although classical cross-reactive carbohydrate determinants are clinically not relevant, α-Gal in red meat through tick bites can lead to severe reactions. Multiple sensitizations to tree nuts complicate the diagnosis and management of patients allergic to peanut and tree nut. This review discusses cross-reactive allergens and cross-reactive carbohydrate determinants in the major food groups, and where available, describes their B-cell and T-cell epitopes. The clinical relevance of these cross-reactive B-cell and T-cell epitopes is highlighted and their possible impact on allergen-specific immunotherapy for food allergy is discussed

Mollusk allergy: Not simply cross-reactivity with crustacean allergens

[Extract] To the Editor, Mollusk allergy is commonly thought of as clinical cross-reactivity after primary sensitization to shrimps, other crustaceans, or mites. Tropomyosin is the major allergen, with primary IgE sensitization in 70% of all shellfish allergies. A high frequency of IgE and basophil reactivity to several mollusk allergens is seen in crustacean and mite-sensitized patients. It is still unclear, however, whether mollusks are capable of producing primary allergic sensitization, or whether IgE reactivity is based solely on cross-reactive crustacean-specific antibodies

Allergenicity of latex rubber products used in South African dental schools

Background: Allergens from latex products in healthcare settings have been known to trigger latex induced allergic reactions in healthcare workers (HCWs). There is a need to quantify individual latex allergens in products in order to assess the allergenicity of latex products used in health care settings, so as to minimize the risk of sensitisation to these proteins. Methods: Fourteen latex examination gloves representing six brands (powdered and non-powdered) and five dental rubber dams from five dental academic institutions were analysed for latex allergens and total protein. Total protein content was determined using the BIORAD DC protein assay kit and natural rubber allergen levels using a capture ELISA assay specific for hev b 1, hev b 3, hev b 5 and hev b 6.02. Results: Hev b 6.02 was found in higher concentrations than other NRL allergens in the products analysed. Hev b 5 content ranged from 0 to 9.2µg/g and hev b 6.02 from 0.09 to 61.5µg/g of sample. Hev b 1 levels were below the detection limit (DL) for 79% of the samples (15/19). Dental dams showed higher allergen levels (median: 80.91µg/g) in comparison to latex gloves (median: 11.34µg/g). Powdered rubber samples also showed higher allergen levels (median: 40.54µg/g) compared to non-powdered samples (median: 5.31µg/g). A statistically significant correlation was observed between total protein and total allergen (r=0.74, p<0.001) concentrations. Conclusion Natural rubber latex (NRL) allergen concentrations differ significantly by product and brand. This study has demonstrated that NRL allergens in latex containing products used in South African dental institutions are present at sufficiently high levels to pose an allergic health risk

Recombinant Tropomyosin from the Pacific Oyster (Crassostrea gigas) for Better Diagnosis

The Pacific oyster is a commercially important mollusc and, in contrast to most other shellfish species, frequently consumed without prior heat treatment. Oysters are rich in many nutrients but can also cause food allergy. Knowledge of their allergens and cross-reactivity remains very limited. These limitations make an optimal diagnosis of oyster allergy difficult, in particular to the Pacific oyster (Crassostrea gigas), the most cultivated and consumed oyster species worldwide. This study aimed to characterise IgE sensitisation profiles of 21 oyster-sensitised patients to raw and heated Pacific oyster extract using immunoblotting and advanced mass spectrometry, and to assess the relevance of recombinant oyster allergen for improved diagnosis. Tropomyosin was identified as the major allergen recognised by IgE from 18 of 21 oyster-sensitised patients and has been registered with the WHO/IUIS as the first oyster allergen (Cra g 1). The IgE-binding capacity of oyster-sensitised patients’ IgE to purified natural and recombinant tropomyosin from oyster, prawn, and dust mite was compared using enzyme-linked immunosorbent assay. The degree of IgE binding varied between patients, indicating partial cross-sensitisation and/or co-sensitisation. Amino acid sequence alignment of tropomyosin from these three species revealed five regions that contain predicted IgE-binding epitopes, which are most likely responsible for this cross-reactivity. This study fully biochemically characterises the first and major oyster allergen Cra g 1 and demonstrates that the corresponding recombinant tropomyosin should be implemented in improved component-resolved diagnostics and guide future immunotherapy

The Anisakis Transcriptome Provides a Resource for Fundamental and Applied Studies on Allergy-Causing Parasites.

BACKGROUND: Food-borne nematodes of the genus Anisakis are responsible for a wide range of illnesses (= anisakiasis), from self-limiting gastrointestinal forms to severe systemic allergic reactions, which are often misdiagnosed and under-reported. In order to enhance and refine current diagnostic tools for anisakiasis, knowledge of the whole spectrum of parasite molecules transcribed and expressed by this parasite, including those acting as potential allergens, is necessary. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we employ high-throughput (Illumina) sequencing and bioinformatics to characterise the transcriptomes of two Anisakis species, A. simplex and A. pegreffii, and utilize this resource to compile lists of potential allergens from these parasites. A total of ~65,000,000 reads were generated from cDNA libraries for each species, and assembled into ~34,000 transcripts (= Unigenes); ~18,000 peptides were predicted from each cDNA library and classified based on homology searches, protein motifs and gene ontology and biological pathway mapping. Using comparative analyses with sequence data available in public databases, 36 (A. simplex) and 29 (A. pegreffii) putative allergens were identified, including sequences encoding 'novel' Anisakis allergenic proteins (i.e. cyclophilins and ABA-1 domain containing proteins). CONCLUSIONS/SIGNIFICANCE: This study represents a first step towards providing the research community with a curated dataset to use as a molecular resource for future investigations of the biology of Anisakis, including molecules putatively acting as allergens, using functional genomics, proteomics and immunological tools. Ultimately, an improved knowledge of the biological functions of these molecules in the parasite, as well as of their immunogenic properties, will assist the development of comprehensive, reliable and robust diagnostic tools.This work was supported by a ‘Collaborations Across Boundaries’ grant and a seed grant from the Centre of Biodiscovery and Molecular Development of Therapeutics, James Cook University (FJB and CC). ALL is an Australian Research Council (ARC) Future Fellow and his laboratory is supported by grants from the National Health and Medical Research Council of Australia (NHMRC). Research in the CC laboratory is supported by grants from the Isaac Newton Trust/Wellcome Trust/University of Cambridge (grant number PNVM/GAAB) and the Royal Society (grant number PNAG/428)